Turning on the heat


Unprecedented in recorded history, there was a 100 degree C difference in temperature between the northern and southern hemispheres last week. While parts of Australia baked in record 50oC heat, in North America hell froze over with the mercury plunging to -50oC.

Somewhere in between in Nepal, heavy winter snow blanketed the mountains last week after a break of almost 12 years. The fact that such snowfall was seen as ‘abnormal’, indicated just how far from the ‘normal’ we have deviated.

The return of winter snow in Nepal and the simultaneous extreme hot and cold in the antipodes actually proves the impact on weather patterns brought by climate change. Most climate models agree that the rise in global average temperature due to the continued emission of carbon dioxide will result in higher rates of temperature rise over land, and particularly in the higher Himalayan regions. The snowline has been migrating upward with rainfall replacing snow, and lowered seasonal snow and ice storage have started limiting melt flow in rivers.

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 As rivers originating in the Himalaya start going dry in the summer season, there is serious concern about rising heat. In a few weeks, temperatures across northern South Asia will start going up. Day-time summer temperature will reach 40oC+ in many places. Nights will not cool down enough, and humidity will also increase. At higher humidity, the human body cannot release heat through sweat evaporation fast enough to cool itself. Most people cannot remain unprotected in the open for more than 6 hours at temperatures above  370C.

A 2014 study of interactions of temperature and humidity in the Indus and Ganga plains by the US-based National Center of Atmospheric Research, and ISET-International found that by 2050, most of June, July and August days and nights will hover above the 370C threshold. A later study by MIT researchers warned of deadly heat waves in the Indo-Gangetic plains, meaning the numbers dying across India, Pakistan and Nepal Tarai in summer will shoot up.

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The rapid degradation of natural ecosystems within and around many of our cities have removed heat sinks. Vehicular emissions, air conditioners, concrete and asphalt pavements, and air pollution trapping heat between buildings continue to raise the temperature in core cities. These urban heat islands will amplify the impact of global warming, with significant impacts on low-income families and the poor living in substandard housing, lacking safe drinking water, basic energy, and without direct access to air conditioning.

Even if air conditioning was affordable for poor and low-income families, running them will require additional energy from over-burdened electricity grids. In Australia’s heat wave last week, the authorities advised residents to delay using washing machines and dishwashers, and requested healthy people to consider keeping their air conditioners at 24oC to save energy. Older model air conditioners also leak HFCs – chemical coolants which are about 7,000 times more potent greenhouse gases than carbon dioxide.

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In Nepal, as global temperature rises, the lower river valleys of the Siwalik and the Mahabharat as well as Tarai plains will see more days when the safe temperature/humidity threshold will exceed 37OC. Even in Kathmandu, June-July-August will have hotter days as global warming combines with the urban heat bubble to make it uncomfortably humid and unsafe.

Nepal’s policies, plans and actions have not yet taken the threat of heat risk seriously. Nor have we begun to  systematically assess changes in local temperatures and humidity regimes.

Reducing the threat of increasing heat requires us to carefully rewire the way we design houses, build infrastructure, deliver and manage energy, forests, grow food, and maintain productivity of small land holders and field workers. Shifting to cleaner forms of energy for cooking and public transportation would give us the flexibility required to minimise growing threat of heat, and adapt.

Urban and rural municipalities can begin working on solutions without waiting for national policies. Local governments have the authority and their programs must emphasise restoration and conservation of natural ecosystems, water sources, and provide incentive for climate-friendly house design and materials. Public health systems need to be better prepared to respond immediately to the elderly, children and pregnant women with heat stress.

Increasing heat and low dry season flow of rivers is going to affect millions living downstream from the Himalaya in Nepal and beyond. In the mid term, developed and giant middle-income countries need to significantly curb emission of greenhouse gases. There is no other way.

And while they mitigate carbon use, we in Nepal need to be prepared for low river flows in the dry season, and find ways to minimise the impact of prolonged heat waves. The more we delay taking action, the higher will be the future cost of measures we will have to take to adapt to the heat.

Ajaya Dixit is Executive Director of Kathmandu based ISET-Nepal. His monthly column Climate for Change deals with the impact of global warming in Nepal.